I consider quercetin a “preclinical panacea,” meaning it shows a lot of potential in laboratory studies but may not translate to real-life benefits. In medicinal chemistry, quercetin is known as a pan assay interference compound. This means it often interacts with many different proteins in lab tests, leading to misleading positive results.
One major challenge in research on quercetin and polyphenols is that most studies use high concentrations not achievable in real life. Many proposed actions of quercetin shown in lab settings may not apply to actual clinical situations. One well-known effect is quercetin’s ability to stabilize mast cells, which are part of the immune system and respond to environmental triggers.
How Quercetin Stabilizes Mast Cells
When mast cells, which are a type of immune cell in our body, get activated, they release chemicals from their storage bubbles called granules. By helping to keep the membranes of these mast cells stable, we can potentially prevent the release of these chemicals.
Some early studies showed that quercetin at concentrations over 10 micromolar can stabilize rat intestinal mast cells, and more recent studies confirmed this for human mast cells as well. This stabilization effect is shared with related compounds like luteolin and bicalin.
Challenges in Reaching Effective Levels
Unfortunately, we cannot reach those high levels of quercetin in the bloodstream through supplements or food sources, making it reasonable to question this as the main way it works. Many earlier studies on quercetin find little useful information because they used concentrations that we cannot achieve in people.
Insights from Animal Studies on Quercetin
Animal studies provide valuable insights because administering quercetin orally can give us a better understanding of its effects in living organisms. Recent animal studies have shown that quercetin can affect the body without relying on mast cells. These studies documented improvements in mood caused by LPS as well as the ability to help relax airway muscles. Quercetin also lowered levels of IL-4 and decreased the activity of NF-kappa B, a protein that boosts other cytokines like IL-6 and TNF alpha.
Quercetin and Gut Microbiome Benefits
Furthermore, some interesting effects of quercetin relate to the gut microbiome. Quercetin supports a diverse microbiome and increases populations of beneficial bacteria like Bacteroides, Lactobacilli, and Bifidobacteria. It also helps produce butyrate, a fatty acid important for gut health and immune function.
One of the rewarding aspects of my work is breaking down potential actions of compounds like quercetin to identify the most likely ones to hold up in real-world applications. For quercetin, I believe its main action likely relates to its impact on NF-kappa B.
The Low Bioavailability High Bioactivity Paradox
This is part of what’s known as the low bioavailability, high bioactivity paradox, which applies to many natural polyphenols. It suggests that how much of a substance we absorb may not be as important as previously thought.
Research indicates that flavonoids like quercetin can change the gut microbiota, which might help explain how they affect heart health, metabolism, and the immune system. We also discussed how quercetin promotes the production of certain compounds, including small phenolic metabolites and butyrate, that may enhance its health benefits.
To summarize, here are three key points about quercetin and polyphenols:
- Clinical trial data shows consistent evidence for quercetin’s benefits on heart and metabolic health.
- There is strong preclinical evidence that quercetin helps immune function by changing cytokine profiles and immune markers. However, only a few human trials have demonstrated its immune benefits, making this an area that needs more study.
- Quercetin works through various mechanisms in the body that affect immune responses and metabolism. To make better use of this information, we need to improve how well quercetin is absorbed in our bodies.
Practical Tips Before Using Quercetin
If you’re thinking about using quercetin, here are some practical tips:
For immune health, ensure you have enough vitamins A, C, D, and zinc before adding quercetin.
Although there’s some evidence that quercetin can help balance blood sugar, it’s better to choose products with stronger research backing, like vitamin D, chromium, or berberine.
For heart health, focus on getting enough omega-3 fatty acids, magnesium, and vitamin D first before trying quercetin.
Remember, good diet, exercise, sleep, and stress management are also essential.
